indicates that nerve continuity exists, and that some regeneration of fibres
will take place.
There are various theories as to the causation of this condition. Some
authorities believe that it is due to a primary ischaemic pare^is^of^yascul^r
origin which is most marked at tne stylomastoid lorame^rThe nerve suffers
Duration of stimulus in mitlisecs.
Fig. 177. Strength-duration curves. A, Normally innervated muscle; B, Denervated muscle.
from malnutrition due.tji_its_j5reiatlyjlimmished blood supply, and ischaemic
paralysis results. Further, this arterial block produces a capillary' dilatation
and an increase in permeability so that a secondary oedema of the nerve
results with its consequent compression in the bony canal. The condition is
always unilateral, and there may be a history of expoaw* ti -colder
on"the affected side.
^PROGNOSIS. This depends Upon the pjresence_pr f^rence nf
grneTarge^majority of cases recover spontaneously or with conservative
treatment, but the degree and duration of the palsy are of importance in
determining the outcom^f the paralysis is complete and has been present
for 2 months some residual loss of movement may occuiŽLoss of electrical
conductivity in a case of complete paralysis persisting for 4 weeks after the
onset is unlikely to be followed by complete recovery of function.
TREATMENT. In a relatively large proportion of patients complete recovery
occurs spontaneously, and treatment is not required in the majority of
patients. This group includes those with an incomplete paralysis of whom
85 per cent regain full function and 15 per cent have a partial recovery of
function. Patients should be observed daily for 7-10 days for signs of
deterioration as indicated by reduction or loss of nerve conductivity. Physio-
therapy in the form of massage of the muscles on the affected side may help
to maintain tone. In cases where recovery may be prolonged the oral muscles